1. Field of the Invention
The present invention relates to a system and method for transmitting and receiving multimedia information, including high-resolution video, audio and data, over an optical network.
2. Background Information
Immersive visualization (IV) theaters provide environments for detailed inspection of intricate images, often in three dimensions and often in true xe2x80x9cimmersivexe2x80x9d settings. Image content can be from various fields of scientific and industrial endeavor, such as from the earth sciences, the manufacturing industry (e.g., automobile, aircraft, earthmoving vehicles), the medical industry, military and government applications, and the like. Immersive visualization theaters are typically multi-million dollar installations with sophisticated projection systems, high-end graphics servers and large, multi-terabyte data sets to be inspected. Often these data sets contain critical information requiring inspection by a group of experts that are geographically distributed. Consequently, there is a need for a collaborative solution.
A typical immersive theater comprises components such as: high-end computer graphics systems (e.g., graphics systems provided by SGI(copyright), SUNS Microsystems, Hewlett Packard, and the like) on which the applications are hosted; sophisticated projection systems, with screens as large as several square feet to tens of square feet (e.g., projection systems provided by BARCO, Panoram Technologies, Fakespace Systems, Christie Digital Systems, Inc., and the like); and several other smaller components, such as, for example, video switches, keyboard/mouse switches, blenders, controllers, and the like.
Wide-area collaboration (i.e., information inspection by a group of experts that are geographically distributed at two or more remote sites) involves replication of the database/server at each of the remote locations and includes the transmission of control signals and xe2x80x9cchangexe2x80x9d information between the various remote sites. In such a collaborative system, the servers at each remote site recalculate any changes and display them individually at the respective remote sites. This is especially difficult in the case of three-dimensional (3D) stereoscopic images, where the server processing power required to render the images is very high (and consequently expensive). Several problems exist with such a wide-area collaborative system. For example, there is no real-time visual collaboration between remote sites, expensive databases need to be reproduced at each center, and the databases need to be updated manually at each location. Alternatively, to avoid the multi-server scenario, the experts can travel to a single location that houses the data and collaborate locally at that location. However, this results in the inefficient use of time due to travel requirements. Consequently, the absence of connectivity and real-time data interpretation, evaluation and decision-making capability between IV islands hinders efficient collaboration.
An example of the critical nature of wide-area collaboration involves oil exploration in the oil and gas industry. Sub-surface characterization models to investigate potential drilling sites can comprise terabytes of time-elapsed multidimensional seismic field data. Tools for storing and displaying these data can exist at IV centers. However, the experts needed for interpreting the data for recommended drilling locations may not necessarily reside at those locations. It is estimated that a mistaken recommendation can cost upwards of several million dollars, making it paramount that the data be viewed, shared and worked on collaboratively by as many scientific and technical experts as possible. A real-time, visual collaboration tool for interpreting these data is of great benefit to this industry.
Visualization centers today are essentially communication islands without the ability to communicate with each other over large distances. This isolation has resulted from several major technological challenges, such as, for example, the inability to provide a low latency solution over long distances. As used herein, latency is defined as the time lapse between transmitting information at one site and displaying the information at a remote site.
Besides a software solution requiring databases at each collaboration location, several attempts have been made at developing hardware-based solutions based on single database locations and transport of the images, as opposed to data replication.
Transportation of the high resolution stereo images over large distances can be accomplished via optical networks. To that end, proprietary protocols or existing transport protocols can be used, along with techniques such as demultiplexing the high bandwidth data into several smaller channels for transport over different wavelengths in a DWDM (dense wavelength division multiplexing) environment. The problems encountered with these techniques include lack of synchronization and the consequent loss of image quality at the receive end. Furthermore, proprietary transport protocols are limited to deployment within local private networks, and cannot be used to transport the images over very large distances through public networks.
Proposed solutions are illustrated in FIG. 1 and represented by ovals 105, 110 and 115. In FIG. 1, latency is plotted as a function of application, with each technology represented by an oval whose location and area represents its range of applicability. Referring to the oval 105 labeled xe2x80x9cOPTICAL (Proprietary Private Network Only),xe2x80x9d the companies that have developed products in this segment include Lightwave Communications, Raritan International, and the like. The oval 110 labeled xe2x80x9cElectricalxe2x80x9d refers to connectivity within a building by electrical rather than optical means. Referring to the oval 115 labeled xe2x80x9cOPTICAL (Packet-Based, e.g., IP Networks),xe2x80x9d the technologies used here include the so-called xe2x80x9cKVM extenders,xe2x80x9d where xe2x80x9cKVMxe2x80x9d refers to xe2x80x9ckeyboard, video, mouse.xe2x80x9d These products are typically based on packet-based Internet Protocol (IP) networks and are known to cause unacceptable latency for some applications. These KVM extenders also have restrictions based on bandwidth throughput, thereby increasing transmission time for large amounts of information.
The proposed solutions represented by ovals 105, 110 and 115 do not meet specific requirements in some markets. These requirement include, for example the ability to: (a) transmit very high resolution images (e.g., 1280xc3x971024) bi-directionally with no artifacts and at high refresh (e.g., 112 Hz); (b) transmit such images across distances that span international boundaries; (c) display such images across multiple (e.g., three) screens; and (d) avoid duplicating data storage at the remote end. The last requirement addresses security. In many applications of IV connectivity, transmitting the actual data may not be acceptable across country borders due to the sensitive nature of the information. These requirements are in addition to the features supported by previous solutions, for example, to send control information from a keyboard, mouse, or joystick (or other similar devices), and to send multimedia information (e.g., video images, data from applications developed for use with Ethernet connections, control and stereoscopic audio, and the like).
The present invention provides an apparatus that interfaces with a visualization graphics-server on one side and the optical network on the other. This Video-to-Optical apparatus, hereinafter referred to as xe2x80x9cV2Oxe2x80x9d, can be used over either a private or a public optical network and transfers the multi-media information in standard SONET/SDH framed format.
In accordance with exemplary embodiments, according to a first aspect of the present invention, the system includes an optical carrier network configured to communicate multimedia information at a bitrate of at least 100 megabits per second (Mbps). The system includes a plurality of optical network elements in the optical carrier network, wherein the combined plurality of optical network elements provide a low latency end-to-end connection. The system also includes a plurality of multimedia visualization centers, respectively coupled to the plurality of optical network elements. Each multimedia visualization center comprises multimedia presentation equipment suitable for creating and presenting multimedia information, and a visualization interface element coupled to a respective optical network element. The visualization interface element comprises a transmission element configured to encode multimedia information into optical SONET payload envelopes for transmission in the optical carrier network, and a receiver element configured to decode multimedia information from the optical SONET payload envelopes into a form suitable for multimedia presentation.
According to a second aspect of the present invention, the visualization interface element contains a transmitter and receiver. The transmitter is located at one end of a optical network line and the receiver is located at the other end.
On the transmitting end, the V2O digitizes the analog video images generated by high-end graphic computers or video transmitters, combines it with audio, control and data inputs into SONET-frames for transmission over an optical network. The SONET transmission rates used in this invention can vary between OC-3 (155 Mbps) and OC-192 (10 Gbps). As SONET is a transmission standard, these signals can be transmitted over existing public networks. Additionally, the same signals can be sent over private networks. The video data transmission rate is determined to match the appropriate signal rate for transmission such as OC-3, OC-12 and OC-48.
On the receiving end, the V2O converts the optical SONET-framed signals back into the constituent information: video, audio, control and data. The regenerated video signals are then displayed on high-resolution screens at the same rate and resolution as the source location. In summary, the V2O provides for real-time global connectivity of visualization centers using public and/or private optical networks with minimum latency achievable in a network.
In accordance with the exemplary embodiments of the present invention, the image transfer apparatus can be placed in an optical network that offers an end-to-end OC-3 or higher rate circuit. A plurality of visualization centers are coupled to the optical network. Each visualization center includes: (i) V2O apparatus that transmits and/or receives SONET frames containing the multimedia information; and (ii) multimedia presentation equipment suitable for displaying audio, video and data.
According to another aspect of the present invention, a SONET payload envelope is structured to include multimedia information to allow encoding at the transmit side and decoding on the receive side of the apparatus. The coding and decoding information provide information relating to the video resolution, refresh rate and blanking intervals in each transmitted SONET frame to accurately synchronize pixel clocks between the transmitter and the receiver elements.
In still another embodiment, MPEG Video Compression techniques and/or Video Frame Dropping Algorithms are supported at the transmission rates of interest, (OC-3 or higher) by the V2O apparatus. Compression techniques allow for the transmission of data using a smaller bitrate, and frame dropping algorithms allow the dropping of one out of N video screens. According to exemplary embodiments, high-resolution images with the appropriate algorithm are transmitted using SONET/SDH through a fiber optic network with a quality of service that supports the lowest possible latency on the path connecting the visualization centers.